by Abbie Carrier
Need to get rid of some mealybugs and looking for help? At first, little tufts of white may not seem like a big deal when they appear on houseplants, fruit plants, succulents. or ornamentals, but chances are these cottony-looking spots are mealybugs. These bugs are soft-bodied, segmented wingless insects that feed on plants by inserting their stylets, long mouth appendages, and sucking the sap out of the infected plant.
While a small infestation may not cause much damage, if the plant starts to yellow and curl, the infestation has begun to weaken the plant. Feeding sites can also become sticky, leading to sooty molds. While a mealybug infestation will take a long time to kill the infected plant, it is easiest to get rid of the bugs when they are found in smaller amounts. When the bugs are not prominent on the plant, it can be more difficult to find a mealybug infestation. Plants that easily fall prey to these fuzzy little critters should be regularly checked so that an infestation does not become harder to deal with.
How to Identify a Mealybug Infestation
Mealybugs affect plants found in warmer growing climates. At first, the infestation may look like mildew or fungus. The female lays its eggs in fluffy white excretions. These eggs hatch after 10 days and then move to different parts of the plant, where they spend the next four to eight weeks developing into the adult form of these bugs.
Mealybugs are white fuzzy things you can see on the stems and leaves. They can also appear cream or brown-colored. These bugs do not fly, so if the bugs fly off when the plant is disturbed, those are most likely whiteflies instead. If the bugs look like little white pieces of fluff and stay put when disturbed, then they are mealybugs.
How to Fight a Mealybug Infestation
Making sure the plants that tend to be targets of mealybug infestations are not overwatered or overfertilized is a key step in making sure the plant is unappealing to these bugs. Mealybugs like plants with high nitrogen levels and soft growth, so avoiding the mealybug-approved environments is important. Mealybugs can also infect the plants around the one currently suffering from a mealybug infestation. If at all possible, the plant that is suffering from the infestation should be separated from other plants that can also fall prey to these bugs.
If the plant that is infested is an outdoor, or greenhouse, plant, then introducing natural predators of the mealybug is an easy way to rid them of the infestation. Some of these insects, such as the ladybug, lacewing, and mealybug destroyer, are commercially available for home gardeners to purchase. Introducing them to the environment would be a way to get rid of the mealybugs without much human intervention. Before doing this, make sure there are no plants in the area you plan to introduce the predatory bugs that would be harmed by their presence. It doesn’t make much sense to introduce an insect to get rid of a pest only to then have to deal with an infestation of the introduced insect instead when it begins to harm another plant.
If introducing predators of mealybugs is not possible, or isn’t effective, these fuzzy bugs should be hosed off the plant with a high-power water stream. Any remaining mealybugs that are visible should be wiped off the plant or dabbed with a Q-tip dipped in rubbing alcohol. Neem oil can also be applied to active infestations. Treating with neem oil will kill mealybugs on contact at any stage of the life cycle—without harming any beneficial bugs, such as honeybees, that are also in the area.
A drop of the neem oil can be applied directly to the bugs (unfortunately, this method can also have negative impacts on beneficial bugs in the area). As an alternative, you can deliver neem oil via a diluted spray of one ounce oil to for every gallon of water, which can be sprayed on the plant every seven to 14 days. Horticultural oil can be used in a similar way to smother eggs and young or adult mealybugs. These oils can be applied to outside gardens and houseplants alike, making them a good option for dealing with these pests wherever they strike.
Another sprayable option when battling a mealybug infestation is using a soapy spray. Mealybugs are armored by a waxy coating, which can make it difficult for treatments to be effective. (Note, however, that they don’t have this waxy coating to protect them until they’ve graduated from the nymph stage.) The soap solution will erode this protective coating and begin to dehydrate the mealybug population, but those harmful effects can translate to your plants, too, so you may want to test this treatment on a small area of your plants before applying to your whole garden plot. Use a quart of soft tap water—hard water won’t be effective due to the minerals it contains—or you can use distilled water mixed with two teaspoons of liquid dish soap. Don’t be tempted to switch the liquid dish soap for dry dish soap or laundry detergent as the chemicals they contain will be detrimental to your plants.
If the infestation is particularly stubborn, a Beauveria bassiana product may have to be applied. This fungus is used in natural-based insecticides, as the spores only have to touch the intended target before infecting the bug and slowly killing it. The Beauveria bassiana fungus targets pest insects, such as whiteflies, aphids, thrips, grasshoppers, and certain types of beetles, while leaving beneficial bugs alone. If the infected plant is a houseplant, make sure the fungus-based insecticide chosen is approved as safe for indoor use. If it is not possible to find one that can be used safely indoors, the other ways to deal with mealybugs we previously discussed may be a better option.
With their fuzzy white appearance, mealybugs don’t look like much of a threat, and when they appear in small numbers, a plant can survive the mealybug infestation. If the bugs start to become more prominent, the chances of the plant dying due to these bugs increases. In an ideal world, the bugs would be dealt with before the negative impact of these bugs is seen, but it is common for an infestation to be overlooked and go unnoticed until the plant starts to turn yellow, droop, and suffer from leaf curl. Leaf curl is distortion of the plant’s leaves as a result of insects feeding on the liquid instead the plant.
To treat afflicted greenhouse plants, the gardener can simply introduce beneficial bugs or a Beauveria-bassiana-based insecticide to deal with the mealybugs, but an infestation on houseplants can also be dealt with by following the tips and tricks laid out here. Unfortunately, mealybugs can be particularly stubborn. If, after three weeks of treatment, the infected plant is still showing signs of infestation, it might be necessary to get rid of the plant completely to stop the bugs from spreading to other plants in the area.
Want to learn more about mealy bugs?
Arbico Organics covers Pest Solver Guide: Mealybugs
SFGate Homeguides covers Soapy Spray to Get Rid of Mealybugs on Houseplants
National Pesticide Information Center covers Neem Oil
I have two large bushes that have mealybug and whiteflies. All the way through the plant. I’ve been using neem oil solution to battle them back. I think I’m winning? At what point do I give up and pull the bushes out. They are large bushes.